There is a half century of history of schemes which have been implemented for improving the efficiency of elevators. Among these are ways of determining which car shall answer a hall call, such as the relative system response dispatchers disclosed in U.S. Pat. Nos. 4,363,381, 4,815,568, to Bittar, and 5,024,295. Others involve peak period dispatching, including zoning and channeling, some of which is disclosed in U.S. Pat. Nos. 4,792,019 and 4,838,384. And, to improve further on such systems, various forms of traffic prediction estimates have been used. The systems become more sophisticated with techniques which have been variously referred to as artificial intelligence, fuzzy logic and so forth. All of the foregoing relate to efficient operation of the elevators within a group.
To achieve more efficient operation of tall buildings (in excess of, say, 20 floors) buildings have been provided with groups of elevators, one group operable only to the lowermost 10 or 15 floors, and the other group operable only in the highest floors of the building, in which case the groups are referred to as the "low rise" and the "high rise". The elevators in the low rise are incapable of reaching a floor in excess of the high end of the low rise. The elevators in the high rise have no access to floors in the low rise: there are no gates; there aren't even any elevator lobbies adjacent to the high rise elevators in the low rise floors. In even taller buildings, there may be low rise, medium and high rise, or even more rises. For exemplary purposes herein, a building having a low rise serving floors 1-13, a medium rise serving floors 14-22, and a high rise serving floors 23-30 will be referred to.
One of the tricks in designing a building is to have a fair estimate of floor usage which will permit predicting how many elevators will be required to serve the various floors, and therefore the grouping of elevators into low, medium and high rises. It isn't just the number of elevators in the building, but their accurate allocation to the correct rises which will prove to be successful or not, in handling the tenant and other traffic amongst the floors of the building.
It has been known to provide a "swing car" which may be swung out of a group (whether the group be the only group in the building or not) so as to operate independently of that group, either in simplex mode with its own riser (a riser consisting of hall call buttons and hall enunciator lanterns) or in another group. Such operation may be to accommodate public access to a rooftop restaurant after normal closing hours of an office building, or preferential floors in luxury hotels and apartments, and the like. Such cars can also provide emergency operation when a group controller ceases to function.
A system capable of swinging an elevator between groups, and from operation within the group to simplex operation, is disclosed in a commonly owned, co-pending application entitled "Elevator Car and Riser Transfer", U.S. Ser. No. 07/853,678, filed on Mar. 19, 1992, by Meguerdichian et al. However, the value that a swing car from one group has in handling traffic in another group is severely hampered by the physical location of the swing car and the need to usher passengers specially to it, typically by means of lobby dispatching personnel. Additionally, the swinging typically has to be anticipated for some significant period of time to make it worthwhile to cause the car to be swung from one group to another. Thus, the use of the swing car is not of much value during rapidly changing traffic patterns (such as during the noon rush of a three-rise building), or handling severely bunched up traffic as may result from the conclusion of a banquet on a restaurant floor, or the conclusion of class time on floors having bulk educational classes, and the like.